Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 35: Focus: Rheology I (joint focus with DRG)

CPP 35.1: Invited Talk

Thursday, March 29, 2012, 15:00–15:30, C 243

Motion of microswimmers governed by light in a fluid flow. — •Philippe Peyla, Salima Rafaï, and Xabel Garcia — Grenoble University and CNRS, LIPHY, BP 87 38 402 Saint Martin d'Heres, France

In nature, organisms that can propel themselves in a fluid medium are ubiquitous. While larger organisms, such as fish, use inertia in their motion, microorganisms like spermatozoa, microalgae or bacteria, move at low Reynolds number, where viscous forces dominate over the effects of inertia. A recent and currently unresolved issue involves understanding the hydrodynamics associated with the individual or collective motion of microswimmers through their fluid-mediated interactions. The motion of these micro-organisms is affected by the presence of gradients (chemiotaxis in the presence of chemicals, gyrotaxis in a gravity field, phototaxis under illumination). In this experimental and theoretical work we show how to use the phototaxis properties of some micro-algae to modify and control the flow of a suspension of microswimmers.